In May of the following year (19^8)^ prior to the spaxming 

 season, the concentration of "yearlings" was considerably re- 

 duced and the larger and older larvae were quite scarce in the 

 long bed of sand and silt (Station 2). The conformity of the bed 

 itself had changed considerably as a result of tJae spring floods, 

 lluch greater nuribers of the "yearlings", and nearly all of the 

 larger (and older) individuals in the area were found in the 

 nearby soft^bottomed channel (Station 3). ^Collections made in 

 the suraner of 19U3, Lniniediately after the spavming soason,-:dis- 

 played a restoration of the concentrations by "size and age of the 

 larvae in these two types of beds. 



These unstable habitats, under the impact of stream flood 

 conditions;"' are. evidently responsible for the dispersal of larvae 

 not o'nly into iffore suitable areas nearby but also throughout the 

 entire lower watershed. Amocoetes are present in the sandy bot- 

 toms of long reaches of the lo^rer river in greater numbers than 

 could be produced in the limited spawning areas present there. 

 They were found to be present in the sandy fan in Ocqueoc Lake 

 ivhere the river empties into that body of water. This site is 

 several miles below the nearest spavming riffle. 



Within that portion or the river where amnocoetes occur most 

 abundantly, a few larvae could be found in almost every location 

 where the bottom permitted burrowing. Pockets of silt and sand 

 between rocks and. behind obstructions provided such locations. 

 Below spaivning areas, some larvae of all sizes were found in pre- 

 cipitous ;, muddy stream banl-cs adjoining areas of swift currents in 

 the stream proper. Areas of fine, compacted sands and ones of 

 gravel occasionally harbored a few young-of-the-year. In late 

 summer and fall, some of the largest larvae and partly transformed 

 sea lampreys take up quarters in many midstream locations in' bur- 

 rows dug in sand amid, the gravel and rubble of the stream channel 

 proper. Such individuals apparently maJce- a change from their 

 customary larval habitat for an unknoivn reason. 



Habits and behavior 



Larvae of the sea lamprey, when ready to leave the nest, 

 work their way out of the sand in which the eggs were imbedded, 

 (in the interstices of the gravel forming the downstream rim of 

 the nest) and enter the current. In spite of violent v/riggling 

 movements;, they are generally no match for the currents prevalent 

 in spaivning riffles and are consequently swept downstream, lihen 

 they are carried into baclcwaters, eddies, or deep pools where 

 sluggish currents or slack water prevail they suddenly dive for 

 the bottom. Such locations generally possess bottoms of silt into 

 which the larvae rapidly burrow. Young-of-the-yeax amnocoetes of 

 the sea lamprey iriien released in the quiet water of an aquarium 

 dove Limediately for the bottom "without apparent regard for the 



- 11;5 - 



